I'm using a cnc table made by me with Mach3
After working well, It began with a problem: don't respect the F command so I set F350 and it was moving the head about 900 mm/minute.

Then, stopping the program, I introduced in the code a sentence as this:
M6 T3 F400
And started from here the program
The machine responded well to the command, moving the machine at the specified velocity.
But, without this, the machine didn't respected the original F command.

What could make that the Mach3 don't respect the F command?

N0010 (Filename: ConectorSuperior.tap)
N0020 (Post processor: Mach3 plasma.scpost)
N0030 (Date: 16/03/2016)
N0040 G21 (Units: Metric)
N0050 G53 G90 G91.1 G40
N0060 F1
N0070 S500
N0080 (Part: ConectorSuperior)
N0090 (Operation: Outside Offset, trazado, T3: Jet tool)
N0100 M06 T3 F350.0  (Jet tool)
N0110 G00 Z10.0000
N0120 X860.8263 Y199.3129
N0130 Z0.0000
N0140 M03
N0150 G02 X855.3957 Y199.3129 I-2.7153 J2.7153 F900.0
N0160 G01 X853.2744 Y201.4343
N0170 X921.1920 Y269.3519
N0180 G03 X921.1920 Y271.8267 I-1.2374 J1.2374
N0190 G01 X793.9128 Y399.1060
N0200 G03 X790.9253 Y397.8685 I-1.2374 J-1.2374
N0210 G01 Y5.0000
N0220 G03 X793.9128 Y3.7626 I1.7500 J0.0000
N0230 G01 X921.1920 Y131.0418
N0240 G03 X921.1920 Y133.5167 I-1.2374 J1.2374
N0250 G01 X855.3957 Y199.3129
N0260 M05
N0270 G00 Z10.0000
N0280 X992.1055
N0290 Z0.0000
N0300 M03
N0310 G02 X986.6749 Y199.3129 I-2.7153 J2.7153
N0320 G01 X984.5536 Y201.4343
N0330 X1052.4712 Y269.3519
N0340 G03 X1052.4712 Y271.8267 I-1.2374 J1.2374
N0350 G01 X925.1920 Y399.1060
N0360 G03 X922.2045 Y397.8685 I-1.2374 J-1.2374
N0370 G01 Y5.0000
N0380 G03 X925.1920 Y3.7626 I1.7500 J0.0000
N0390 G01 X1052.4712 Y131.0418
N0400 G03 X1052.4712 Y133.5167 I-1.2374 J1.2374
N0410 G01 X986.6749 Y199.3129
N0420 M05
etc
.
.
.

N1190 G00 Z10.0000
N1200 M05 M30

(The T3 had been used before at 900 mm/min, but even reloading the program was failing)